The current minimum wage is $15.75 per hour, but New Zealand First wants it to rise by more than a quarter to $20 per hour.

That's much higher than the other parties want to see it - the Greens want it set at $17.75 per hour and Labour want it set at $16.50 per hour.

When asked if he would be happy to raise the minimum wage to $20 per hour, Mr English replied: "We'll deal with that later."

Ms Ardern says she wants to "leave the discussions to the negotiating table", but says she and Mr Peters "share a focus on lifting the wages of those who, at the moment, are struggling on the lowest wages".

While a 27 percent increase to minimum wage seems like a massive, almost impossible leap, New Zealand First has been able to get this before.

During their confidence-and-supply agreement with Labour in 2005, the minimum wage rose from $9 up to $12 in just three years.

First Union is on board, but surprisingly businesses are partially on board too, because the policy includes a tax cut.

If businesses are to afford the rise, New Zealand First would also cut companies' tax from 28 percent to 25 percent. It would be even lower for export-generated revenue, at 20 percent.

However, that would be a cost to government and both sides will have to search for room in their budgets to accommodate it.